Affected by the geographical location，hydrometeorology，topography and geomorphology，flood disasters occur frequently in Chongming Island of Shanghai. Especially，due to the lack of drainage outlets in the north and central part of the island，it cannot meet the requirements of drainage during the rainstorm.To scientifically evaluate the influence of the four sluices outward relocation project of Chongming Island on the dynamic conditions of water and sediment in this area，we carry out numerical modeling of hydrodynamics and morphology. Combined with the measured hydrological and sediment data in this area in recent years，we analyze the characteristics of hydrology，sediment，and river regime evolution in this reach，and study the characteristics of water and sediment movement in the engineering reach. Meanwhile，we establish a three-dimensional numerical model of water，and sediment in the engineering reach to simulate and calculate the implementation effect of the plane scheme of flood control and de-watering project along the north side of Chongming Island in the lower section of the North Branch based on model calibration and verification. The results show that the implementation of the project has little influence on the flow condition of the surrounding water areas and the bed evolution of the surrounding water area and the North Branch channel. This study provides technical support for engineering construction.